1)
2)
set.seed(2)
coeff = c(-1.6,-.64)
returnedCoeff = ARMAtoMA(ar=coeff,lag.max = 20)
returnedCoeff
## [1] -1.6000000 1.9200000 -2.0480000 2.0480000 -1.9660800 1.8350080
## [7] -1.6777216 1.5099494 -1.3421773 1.1811160 -1.0307922 0.8933532
## [13] -0.7696581 0.6597070 -0.5629500 0.4785075 -0.4053240 0.3422736
## [19] -0.2882304 0.2421135
set.seed(2)
ARMAacf(ma=(returnedCoeff),lag.max = 3)[1:4]
## 0 1 2 3
## 1.0000000 -0.9747543 0.9190079 -0.8458620
3)